The present invention generally relates to generally relates to image processing systems, and more particularly to an image processing system such as an image filing system, a desk top publishing system and a facsimile machine and is capable of correcting an inclination or skew of an image which is input from an image scanner, an optical disk or the like.
When inputting an image to an image processing system such as an image filing system and a desk top publishing system, the image is read from a recording medium such as an optical disk which is prerecorded with the image or the image is read by a an image scanner which scans a document. For example, when the document is set obliquely to the image scanner or the image is copied with an inclination on the document itself, the image is input to the image processing system in the inclined state. As a result, when the input image is displayed on a display or printed on a printer, the displayed or printed image looks poor.
Conventionally, there are various methods of correcting the inclination of the input image. According to one method, an operator monitors the image which is displayed on the display of the image processing system and makes an eye measurement of the inclination of the image. Then, the operator inputs numerical data on the inclination angle by use of a keyboard or a pointing device which will hereinafter be referred to as a mouse. The entire image is rotated for a rotation angle which is equal to the inclination angle by a rotation operation so as to correct the inclination of the image. On the other hand, according to another method, a rotation angle for one rotation operation is fixed and the operator instructs an arbitrary number of rotation operations from the keyboard or mouse while monitoring the image on the display.
But according to these methods, the inclination angle of the image is determined by the eye measurement of the operator. For this reason, it is impossible to accurately determine the inclination angle of the image. In addition, because the rotation operation involves a trail and error process to correct the inclination of the image, it takes a long time to complete the correcting operation. For example, when correcting the inclination of the image on a size A4 paper, it takes approximately 30 seconds to 2 minutes to complete one rotation operation. Hence, even if the size of the image is reduced on the display, it still takes approximately 5 seconds to complete one rotation operation.
Furthermore, it is often difficult to determine a reference position on the display for use as a reference when rotating the image to correct the inclination of the image. Hence, the operator must be skilled in order to make an appropriate correction.
Therefore, there is a demand for an image processing system which can quickly and accurately correct the inclination of the image by a simple operation without the need for a skilled operator.